Network devices are applied and needed in a plurality of networks. Customers enjoy a plurality of services from different ISPs via many CPEs, the CPEs being maintained, configured, and updated by the ISP as part of their management function. In general, when an ISP needs to upgrade or configure its CPE, it can telnet the CPE to login in and manage the CPE as long as the IP address of the CPE is accessible by the ISP. However, now it is more difficult for many ISPs to get the IP address of most CPEs directly even if the CPEs are under the management of the ISPs because more and more companies today are using private addresses within the LAN and communicate with internet via a network address translation (NAT) server. This causes difficulties for the ISP to manage the CPEs. In addition, it is difficult for one ISP to identify the quantity of CPE belonging to itself and confusion may occur between CPEs that belongs to different ISPs. Meanwhile, the default telnet port is generally fixed at Port 23, which may also bring potential security vulnerabilities.
It is desirable to provide a CPE into which an ISP can login remotely via telnet port assigned randomly, and method of remote login to solve the problems mentioned above.